Aspinall Courthouse: 

GSA’s Historic Preservation 

and Net-Zero Renovation

Case Study

Prepared by The National Renewable Energy 

Laboratory in partnership with the General Services 

Administration on behalf of the Federal Energy 

Management Program

R. Chang, S. Hayter, E. Hotchkiss, 

S. Pless, J. Sielcken, and C. Smith-Larney 

October 2014
ii

Contacts

Jason Sielcken

General Services Administration

1 Denver Federal Center, Bldg. 41, Rm. 240

Denver, CO 80225

Phone: (303) 236-2972

E-mail: Jason.Sielcken@gsa.gov

Shanti Pless

National Renewable Energy Laboratory

15301 Denver West Parkway

Golden, CO 80401

Phone: (303) 275-3000

E-mail: Shanti.Pless@nrel.gov

Cover photo: Aspinall Courthouse, Grand Junction, Colorado. Courtesy of Sunsense Solar.
iii

Acknowledgments

This document was prepared by the U.S. Department of Energy’s National Renewable Energy Laboratory

(NREL) in partnership with the General Services Administration (GSA) on behalf of the Department of 

Energy’s Federal Energy Management Program (FEMP). The team is grateful to Sarah Jensen, FEMP’s 

Sustainability lead, for making the Aspinall Courthouse case study and this document possible. The team 

also thanks all of the authors and reviewers, especially Alicen Kandt and Jimmy Salasovich at NREL, for 

their contributions. 
iv

Abbreviations and Acronyms

ACHP Advisory Council on Historic Preservation

ARRA American Recovery and Reinvestment Act of 2009

ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers

Btu British Thermal Units

E.O. Executive Order

FEMP Federal Energy Management Program

GSA General Services Administration

HVAC Heating, Ventilation, and Air Conditioning

M&V Monitoring and Verification

NHPA National Historic Preservation Act

NPS National Park Service

NREL National Renewable Energy Laboratory

PV Photovoltaic

SHPO State Historic Preservation Office

ZEB Zero-Energy Building
v 

Contents

Acknowledgments...................................................................................................................................................... iii

Abbreviations and Acronyms....................................................................................................................................iv

Executive Summary...................................................................................................................................................vii

1 Introduction .......................................................................................................................................................... 1

1.1 Net-Zero and Historic Properties .........................................................................................2

1.2 Net-Zero Energy ..................................................................................................................2

1.3 Historic Preservation ............................................................................................................5

1.4 Net-Zero Design Complements Basic Design Principles of Historic Buildings .................7

2 Aspinall Courthouse Project Background.......................................................................................................... 9

2.1 Building History...................................................................................................................9

2.2 Project Goals ......................................................................................................................11

3 Aspinall Courthouse Renovation Process.........................................................................................................12

3.1 Design-Build Contracting ..................................................................................................12

3.2 Principles of Net-Zero Design and Operations ..................................................................13

3.3 Implementation of Renovation Measures ..........................................................................15

3.4 Historical Measures ...........................................................................................................15

3.5 Innovative Solutions ..........................................................................................................21

3.6 Commissioning Operations ................................................................................................23

4 Lessons Learned .................................................................................................................................................27
vi 

List of Figures

Figure 1. Federal building use (gross square feet) by building type ....................................................................... 3

Figure 2. Illustrations of ZEB A classification (top) to ZEB D (bottom)................................................................ 4

Figure 3. The Aspinall Courthouse lobby circa 1938 ............................................................................................... 6

Figure 4. Aspinall Courthouse, circa 1938 ................................................................................................................ 9

Figure 5. Aspinall Courthouse light well in the rear of the building, circa 2012 .................................................10

Figure 6. A modeled rendering of the Aspinall Courthouse façade ......................................................................14

Figure 7. Lobby in 1938 ............................................................................................................................................16

Figure 8. Lobby pre-construction (2010).................................................................................................................16

Figure 9. 123-kW PV roof-mounted system ............................................................................................................17

Figure 10. Aspinall Courthouse, north elevation, post-construction 2013............................................................18

Figure 11. Lobby post-construction in 2013............................................................................................................19

Figure 12. Tenant space pre-construction, 2010 .....................................................................................................20

Figure 13. Tenant space post-construction, 2013....................................................................................................20

Figure 14. Modeled end-use electrical consumption in the Aspinall Courthouse ................................................23

Figure 15. Actual end-use electrical consumption as of February 2014 ...............................................................23

Figure 16. Energy use intensity comparison (March 2013–February 2014) ........................................................26

List of Tables

Table 1. Modeled Monthly Energy Consumption and Production .......................................................................14

Table 2. Baseline Versus Proposed Design Elements..............................................................................................19
vii 

Executive Summary

The Federal government is mandated with improving 

efficiency of buildings, incorporating renewable energy, and 

achieving net-zero energy operations where possible. As the 

largest owner of Federal buildings, the General Services 

Administration (GSA) is charged with managing and 

preserving buildings—more than one-quarter of which are 

listed or eligible for historic designation—in an efficient and 

sustainable manner. This challenge led GSA to consider 

aligning historic preservation renovations with net-zero 

energy goals. The agency chose the Wayne N. Aspinall 

Federal Building and U.S. Courthouse, to prove that net-zero 

energy goals can be achieved not only in an older building, 

but one that has a bevy of preservation requirements from 

being listed on the National Register of Historic Places.

The Wayne Aspinall Federal Building is a three-story building 

with nearly 42,000 square feet of office space located in 

Grand Junction, Colorado. The building was constructed in 

1918 and originally functioned as a post office and

courthouse. The building was listed on the National Register 

of Historic Places in 1980 and currently houses nine Federal

agencies. Heavily in need of extensive repairs, the building 

was nearly slated for disposal; however, funding from the 

American Recovery and Reinvestment Act of 2009 (ARRA) 

paved the way for a major renovation project, focusing on 

historic preservation and energy efficiency upgrades. GSA 

aligned its sustainability and environmental goals with historic 

preservation requirements, necessitated by the Aspinall 

Courthouse’s designation on the National Register of Historic Places. GSA leadership is aggressively 

pursuing avenues to eliminate—not just limit—the Federal government’s impacts on the natural 

environment. 

Through a design-build contract, the renovation project successfully met historic preservation 

requirements, the Guiding Principles for High Performance and Sustainable Buildings, and achieved goals 

towards reaching net-zero energy. In fiscal year 2008, prior to renovation, the site energy use intensity 

was 42.6kBtu/ft2 and the annual energy cost was $0.79/ft2

. Post-renovation energy use intensity, as of 

February 2014, was 21kBtu/ft2

, with an annual energy cost of $0.53/ft2. The utility rate structure currently 

does not account for time-of-use or the rooftop photovoltaic system, which would lower the overall cost 

of the PV system. GSA expects that continued attention to energy-efficient operations and maintenance 

will reduce energy consumption and associated costs even further at the Aspinall Courthouse. The 

building currently achieves a status of a zero-energy building with the help of renewable energy both 

purchased from the utility and generated onsite. 

This case study details the lessons learned from this unique achievement of both net-zero and historic 

preservation goals with the hope that facility managers across the country will be encouraged to set 

aggressive energy efficiency or net-zero goals for facilities that may be designated for historic 

preservation. The Aspinall Courthouse renovation is both preserving history and making history as the 

Federal government’s first deep retrofit of a historic building that targets net-zero operations. 

Project Overview

Owner: 

U.S. General Services Administration 

Occupiers: 

U.S. Courts, U.S. Probation, U.S. Marshals, 

U.S. Army Corps of Engineers, one of 

Colorado’s state Senators, FBI, U.S. 

Attorneys, IRS and GSA 

Project Team: 

General Contractor & Architect 

The Beck Group 

Engineer, Lead & Historic Preservation 

Architect, Green Building consultant 

Westlake Reed Leskosky 

Design review & construction management 

Jacobs 

ME Group commissioning 

Project Goals: 

Successfully create GSA’s first net-zero 

historic renovation 

Highlighted Measures: 

Efficient electric and mechanical systems 

A geothermal heat pump 

High-efficient lighting 

Advanced metering and building controls 

A thermally enhanced building envelope 

Solar photovoltaic roof system 

Restored architectural features 

Restored original artwork 
1 

1 Introduction

The General Services Administration (GSA) was established in 1949 to streamline administrative work of 

the U.S. Federal government. According to the GSA, the agency provides Federal facilities to more than 1 

million civilian workers, oversees the preservation of more than 480 historic buildings, and supports 

procurement of goods and services from a broad range of commercial vendors.1 GSA owns and leases in 

excess of 354 million square feet of space in 9,600 buildings in more than 2,200 communities nationwide 

and manages properties that encompass a vast array of building types, including land ports of entry, 

courthouses, laboratories, post offices, and data processing centers.

2 According to GSA, “more than one 

fourth of GSA’s 1,600 owned buildings are listed in or eligible for the National Register of Historic 

Places, the nation’s listing of historic properties, and approximately half are more than 50 years old.”3

With such a large portfolio of historic buildings, GSA is faced with the challenge of managing an aging 

building stock and preserving a large number of the nation’s historic properties. 

The Federal government is mandated with improving efficiency of buildings, incorporating renewable 

energy, and achieving net-zero energy operations4 where possible. These challenges led GSA to consider

aligning historic preservation renovations with net-zero energy goals. The Wayne N. Aspinall Federal 

Building and U.S. Courthouse (Aspinall Courthouse) in Grand Junction, Colorado, is an example of a 

renovation project that aimed to accomplish both historic preservation and net-zero energy goals. 

When Congress enacted the American Recovery and Reinvestment Act (ARRA), $4.5 billion was 

allocated to convert Federal buildings to high-performance green spaces, and another $750 million was 

allocated to Federal building and courthouse renovations. Prior to receiving its portion of this funding, 

GSA was faced with the reality of managing an aging building badly in need of renovation, in the absence 

of the resources available even to consider such a project. Unable to support it, GSA was on the verge of 

disposing the old building when ARRA funds enabled GSA to change course to undertake the Aspinall 

Courthouse historic preservation and net-zero renovation project. This renovation is not only preserving 

history, it is making history, as the Federal government’s first deep retrofit of a historic building that 

targets net-zero operations. 

GSA has aligned its sustainability and environmental goals with historic preservation, necessitated by the 

Aspinall Courthouse’s designation on the National Register of Historic Places. GSA leadership is 

aggressively pursuing avenues to eliminate, not just limit, the Federal government’s impacts on the 

natural environment. GSA’s FY 2012 Sustainability Plan reinforces this commitment: 

GSA remains committed to leading the federal government towards a more sustainable 

future. GSA recognizes the important role it plays in facilitating sustainability goal 

achievement for other federal agencies. GSA will continue to identify and make available 

innovative, cost effective, and sustainable solutions for federal agencies. GSA will also 

continue to examine ways in which it can use its sustainability efforts to improve 

transparency of its operations; reduce costs and eliminate waste; improve accountability 

 

1 GSA Website: www.gsa.gov/portal/content/103369, Accessed September 23, 2014. 2 GSA Website: www.gsa.gov/portal/content/103369, Accessed September 23, 2014. 3 GSA Website: www.gsa.gov/portal/content/104832?utm_source=PBS&utm_medium=printradio&utm_term=historicbuildings&utm_campaign=shortcuts Accessed Feb 25, 2014. 4 As required by Executive Order 13514 and the Energy Independence and Security Act.
2 

and agency performance management; and fully integrate sustainability into its day-today operations.5

GSA’s ability and determination to align the historic preservation requirements that attend the Aspinall 

Courthouse with the agency’s sustainability goals can serve as a guide for other Federal agencies to 

successfully manage similar projects. By highlighting the historic renovation of the Aspinall Courthouse, 

the U.S. Department of Energy’s Federal Energy Management Program (FEMP) hopes that more Federal

agencies will pursue net-zero projects for historic renovations. Each success brings net-zero building 

renovation and operation closer to the status quo, moves the Federal government closer to sustainable 

operations, and increases the nation’s energy security.

1.1 Net-Zero and Historic Properties

The broad scope of the Aspinall Courthouse renovation project was developed to support the GSA’s

commitment to meet and surpass Federal requirements related to net-zero energy and sustainability goals.

It lends context to the historic preservation element of the Aspinall story. 

1.2 Net-Zero Energy

In 2012, nearly 40% of the total U.S. energy consumption (measured in British thermal units [Btu]) 

occurred in residential and commercial buildings.6 In commercial buildings, heating, ventilation, and air 

conditioning (HVAC) account for more than 1 trillion Btu, and lighting accounts for 1.3 trillion Btu.

7

According to the Federal Real Property Profile, the Federal government owned and operated 3.3 billion 

square feet of property with a total of 361,000 building assets and a total operating cost of just over $24 

billion.8 Figure 1 illustrates the types of buildings that are owned and leased by the Federal government; 

offices comprise the largest building type within the Federal portfolio.

The greatest proportion of U.S. energy consumption is associated with buildings, and the Federal 

government is the largest owner and operator of buildings in the United States. The combination presents 

a potent Federal sector opportunity for large-scale energy reduction. With a building stock that includes 

every major building type in all climate zones, extensive industry partnerships, and personnel specially 

trained for world-class building systems research, the Federal government is in a unique position to lead 

the zero energy buildings initiative. Recent mandates and Executive Orders (E.O.s) acknowledge the need 

to ratchet up energy efficiency and the use of renewable energy. 

 

5 GSA FY 2012 Sustainability Plan 

www.gsa.gov/portal/mediaId/162943/fileName/GSA_FY2012_Sustainability_Plan.action 6 U.S. Energy Information Administration; www.eia.gov/tools/faqs/faq.cfm?id=86&t=1. Accessed Feb 2014. 7 U.S. Energy Information Administration, Annual Energy Review 2011, Figure 2.11: 

www.eia.gov/totalenergy/data/annual/pdf/aer.pdf. Accessed Feb 2014. 8 GSA Frequently Asked Questions about the Federal Real Property Profile (FRPP) 

www.gsa.gov/portal/content/104199. Accessed September 2014.
3 

Figure 1. Federal building use (gross square feet) by building type 

Source: Federal Real Property Profile, GSA

The Energy Independence and Security Act of 2007 requires all new Federal buildings and major 

renovations to reduce fossil fuel-generated energy consumption over the next 16 years. Reductions are

measured in comparison to a similar building in FY 20039 and designs for new Federal buildings and 

major renovations must eliminate fossil fuel-generated energy use altogether (or achieve net-zero) by 

2030. E.O. 13514, Federal Leadership in Environmental, Energy and Economic Performance, expands on 

Federal energy reduction and environmental performance requirements set in E.O. 13423, as well as 

outlines specific management strategies to improve sustainability, including managing existing buildings 

to reduce energy, water, and materials consumption. E.O. 13514 requires agencies to implement highperformance sustainable Federal building design, construction, operation and management, maintenance, 

and deconstruction by:

Ensuring all new Federal buildings, entering the design phase in 2020 or later,

are designed to achieve zero net energy by 2030 [Section 2(g)(i)]

The net-zero design goal provides an optimal framework to support E.O. 13514’s principal objective “to 

establish an integrated strategy towards sustainability in the Federal Government and to make reduction 

of greenhouse gas emissions a priority for Federal agencies.” Successfully planning and managing netzero operations requires extensive integration of all building systems, resource use, and building occupant 

behaviors. In fact, net-zero operations can only be achieved through careful consideration of all energy 

use aspects of a building. Additionally, the net-zero design process satisfies the planning requirements of

E.O. 13514 clause (g) implement high performance sustainable Federal building design. Clause (g) 

requires Federal agencies to comply with the Guiding Principles for Federal Leadership in High 

Performance and Sustainable Buildings; any net-zero energy building already complies with the Guiding 

 

9 Similar buildings in FY03 as measured by the Commercial Buildings Energy Consumption Survey or the 

Residential Energy Consumption Survey data from the U.S. Department of Energy’s Energy Information Agency. 

 -

 100,000,000

 200,000,000

 300,000,000

 400,000,000

 500,000,000

 600,000,000

Gross Square Feet

Leased

Owned
4 

Figure 2. Illustrations of ZEB A 

classification (top) to ZEB D (bottom)

Credit: Marjorie Schott, NREL

Principles by virtue of the processes and integration that are required first to reach net-zero feasibility and 

then to achieve net-zero operations.

A zero-energy building (ZEB) or a net ZEB is defined as “a 

building that has greatly reduced energy needs through efficiency 

gains such that the balance of energy needs can be supplied with 

renewable technologies.”10 Typically the definition of net ZEBs

applies to the annual consumption and generation on site. 

ZEBs can be classified in a hierarchical system, from “A” to “D,” 

based on the renewable energy location with respect to the building 

(onsite versus offsite). Figure 2 illustrates the ZEB hierarchy. The 

hierarchical approach emphasizes the following: ZEB A—a 

building that generates and uses energy through energy efficiency 

and building-sited renewable energy systems; ZEB B—a building 

that generates and uses energy through energy efficiency and 

renewable energy sited on the building and on the

property/campus; ZEB C—a building that generates and uses 

energy through energy efficiency and renewable energy sited on 

the building, on the property/campus and offsite; and ZEB D—a 

building that conserves energy through efficiency measures, and 

generates energy through energy renewable energy sited on the 

building, onsite and through the purchase of offsite renewable 

energy credits. 

A grid-connected ZEB uses the utility for energy balance, drawing 

energy from the grid when onsite generation from renewable 

sources does not meet loads, and exporting excess energy back to 

the grid when onsite generation is greater than the building’s loads. 

ZEB designs should always address demand first by using all 

possible cost-effective energy efficiency strategies to reduce it, and 

then incorporate renewable energy to supply the remaining load. 

The Federal government is targeting net ZEBs through innovative 

agency planning and action. It is important that the government 

lead by example and lay the groundwork to make net ZEBs

accessible to private markets. The Federal government’s building infrastructure can demonstrate the 

innovative processes and emerging technologies that are not only making net-zero energy possible, but 

revealing and underscoring its desirability from both an economic and sustainability standpoint. Obstacles

can be avoided in future planning by applying lessons learned to increase efficiency through proven 

energy savings and integrative techniques. 

Each net-zero energy project that the Federal government successfully completes, whether it is a new 

building or a renovation, can serve as a set of valuable lessons for future projects. Given the aging Federal

building stock, and the growing number of buildings eligible for historic preservation designation, the 

reconciliation of net-zero energy measures and sustainability goals with principles of renovation that 

 

10 Torcellini, P.; Pless, S.; Deru, M.; Crawley, D. (2006). Zero Energy Buildings: A Critical Look at the Definition. 

NREL/CP-550-39833. Golden, CO: National Renewable Energy Laboratory. Accessed September 22, 2014:

www.nrel.gov/docs/fy06osti/39833.pdf 
5 

preserve and restore historic building components will be on 

the rise. Not surprisingly, integrating historic preservation 

requirements into net-zero design elements will assist the 

government in achieving multiple goals.

1.3 Historic Preservation

The National Historic Preservation Act of 1966 (NHPA) 

established the National Register of Historic Places, the 

National Historic Landmarks, and the State Historic 

Preservation Offices (SHPOs). The term “historic property” 

is defined in the NHPA as “any prehistoric or historic 

district, site, building, structure, or object included in, or 

eligible for inclusion on the National Register.” As such, 

historic properties may include “artifacts, records, and 

remains which are related to such districts, sites, buildings, structures, or objects.” Listing in the National 

Register is a formal recognition of a property’s historical, architectural, or archeological significance, and 

provides opportunities for specific preservation incentives, which might include Federal preservation 

grants for planning and rehabilitation, Federal historic tax credits, preservation easements held by 

nonprofit organizations or government entities, building fire and life safety code alternatives, and 

potential state tax benefits and grant opportunities.11

Historic preservation involves the public and private sectors operating at local, state, and national levels. 

A key set of agencies and organizations administer and advocate for historic preservation within the 

public and private sectors:

• The National Park Service (NPS) is the principal Federal agency responsible for preservation 

programs and activities and administers the National Register of Historic Places. NPS has 

published a document titled Illustrated Guidelines on Sustainability for Rehabilitating Historic 

Buildings,

12 which details guidelines for implementing a variety of sustainability measures on 

historic buildings, including solar photovoltaics (PV). 

• In establishing a Federal policy for the preservation of cultural and historic resources, and 

creating the National Register, the NHPA also established an agency to support them—the 

Advisory Council on Historic Preservation (ACHP), whose primary role is to comment on 

Federal undertakings that affect historic properties, as required in Section 106 of the NHPA. The

ACHP joins NPS as the other principal public preservation agency at the national level. The 

ACHP reviews and comments on Federal projects that affect properties determined eligible for 

listing on the National Register of Historic Places. 

• SHPOs administer the resources and programs of the national historic preservation program for 

the benefit of citizens, communities, and organizations in each of the 50 states and territories. 

Tribal Historic Preservation Offices may assume any or all SHPO functions on tribal lands on 

behalf of a Federally recognized tribal community. Local historic preservation commissions 

 

11 Kandt A; Hotchkiss, E; Walker, A.; Buddenborg, J.; Lindberg, J (2011). Implementing Solar PV Projects on 

Historic Buildings and in Historic Districts. NREL/TP-7A40-51297, Golden, CO: National Renewable Energy 

Laboratory.

12 Grimmer, A.; Hensley, J; Petrella, E.; Tepper, A; (2011).The Secretary of The Interior’s Standards for 

Rehabilitation & Illustrated Guidelines on Sustainability for Rehabilitating Historic Buildings. U.S. Department of 

the Interior, National Park Service, Technical Preservation Services. Accessed July 23, 2014: 

www.nps.gov/tps/standards/rehabilitation/sustainability-guidelines.pdf 

While preservationists use 

many tools in the designing 

and planning process for 

historic renovations to meet 

various regulations, a 

valuable asset can be 

archived photographs, like 

the one shown in Figure 3.
6 

review projects under local preservation ordinances. Some of these local commissions are 

Certified Local Governments, which receive support from the NPS in partnership with SHPOs. 

• The National Trust for Historic Preservation (National Trust) serves as the only national nonprofit 

dedicated to historic places. Statewide and local preservation nonprofit organizations provide 

advocacy, technical assistance, and education programs at the respective levels. National Trust 

programs combine historic preservation and economic development to promote downtown and 

neighborhood revitalization. 

Figure 3. The Aspinall Courthouse lobby circa 1938

Source: GSA

The Federal, state, and local stakeholders operate within a set of guidelines for the preservation of historic 

properties known as the Secretary of the Interior’s Standards for the Treatment of Historic Properties 

(Secretary’s Standards), as well as with Federal, state, and local preservation laws. Only Federal agencies 

or projects with Federal involvement are required to use the Secretary’s standards. The Secretary’s 

standards are neither technical nor prescriptive, but are intended to promote responsible preservation 

practices and provide consistency to the preservation of historic materials and features of historic 

properties. The Secretary’s Standards for Rehabilitation (hereafter, the “Secretary’s Standards”) are 

summarized below:

1. A property will be used as it was historically or be given a new use that requires minimal change 

to its distinctive materials, features, spaces, and spatial relationships.

2. The historic character of a property will be retained and preserved. The removal of distinctive

materials or alteration of features, spaces, and spatial relationships that characterize a property

will be avoided.

3. Each property will be recognized as a physical record of its time, place, and use. Changes that 

create a false sense of historical development, such as adding conjectural features or elements 

from other historic properties, will not be undertaken.

4. Changes to a property that have acquired historic significance in their own right will be retained

and preserved.
7 

5. Distinctive materials, features, finishes, and construction techniques or examples of 

craftsmanship that characterize a property will be preserved.

6. Deteriorated historic features will be repaired rather than replaced. Where the severity of 

deterioration requires replacement of a distinctive feature, the new feature will match the old in

design, color, texture, and, where possible, materials. Replacement of missing features will be

substantiated by documentary and physical evidence.

7. Chemical or physical treatments, if appropriate, will be undertaken using the gentlest means 

possible. Treatments that cause damage to historic materials will not be used.

8. Archeological resources will be protected and preserved in place. If such resources must be

disturbed, mitigation measures will be undertaken.

9. New additions, exterior alterations, or related new construction will not destroy historic materials, 

features, and spatial relationships that characterize the property. The new work shall be

differentiated from the old and will be compatible with the historic materials, features, size, scale

and proportion, and massing to protect the integrity of the property and its environment.

10. New additions and adjacent or related new construction will be undertaken in such a manner that, 

if removed in the future, the essential form and integrity of the historic property and its 

environment will be unimpaired. 

1.4 Net-Zero Design Complements Basic Design Principles of Historic Buildings 

While the combination of executing a historic preservation and net-zero renovation may at first seem 

doubly daunting, these two concepts are actually closely aligned. The basic design principles used in the 

majority of historic buildings is nearly identical to those suggested by ASHRAE in the Advanced Energy 

Design Guides. The guides are a series of publications designed to provide recommendations for 

achieving energy savings over the minimum code requirements of Standard 90.1, the first step in the 

process toward achieving a net ZEB. The guides focus on different building types, but in general target 

passive design elements, such as insulation, maximizing daylighting, etc. 

Energy design strategies suggested by the ASHRAE’s Advanced Energy Design Guides include: 

• Passive solar design

• High-performance building envelope (detailed consideration of glazing, insulation, and thermal 

breaks)

• Consideration of static building elements and landscape elements to assist in solar shading and 

natural ventilation

• [Utilizing] form with modular elements for maximum air flow efficiency.

In many instances historic building designs naturally integrated these concepts. For instance, buildings 

were already oriented to maximize daylighting and to provide as much thermal comfort as possible in the 

absence of electricity and central air conditioning. Often, historic buildings located in cold climates are 

south facing and have large windows on the south façade to allow for both daylighting and heat gain from 

the sun. Large thermal mass of building materials provides heat absorption and slower release of heat in 

winter months. In a sense, the principles of building design have come full circle as architects and 

engineers focus on maximizing the use of natural sources for lighting, heating/cooling and ventilation 

through design elements to reduce energy loads and reach net-zero operations. This same focus on 

maximizing the use of natural sources was essential to building design before the technological age. Thus, 

the goals of net ZEBs and historic buildings align well. 
8 

The Aspinall Courthouse is a prime example of applying goals to meet sustainability, net-zero, and 

historic renovation goals. Post renovation, the Aspinall Courthouse is anticipated to: 

• Use 40% less water than a comparable office building. 

• Use 67% less energy than a minimally code-compliant building. 

• Generate 100% of its energy onsite through use of a roof-mounted solar PV array.

The following sections summarize the Aspinall Courthouse renovation project, an example of a successful 

Federal historic property that achieved sustainability and net-zero energy goals, without compromise to 

the Secretary’s Standards. 
9 

Figure 4. Aspinall Courthouse, circa 1938

Source: GSA

2 Aspinall Courthouse Project Background 

The Wayne Aspinall Federal Building is a three-story building with nearly 42,000 square feet of office 

space located in Grand Junction, Colorado. The building was constructed in 1918 and originally 

functioned as a post office and courthouse. A large extension was added in 1939, and the building was 

listed on the National Register of Historic Places in 1980.

13 It currently houses nine Federal agencies.

With funding from ARRA, GSA initiated a major renovation of the Aspinall Courthouse, focusing on 

historic preservation and energy efficiency upgrades. The project was completed in 2013. 

2.1 Building History

In June 1910, the U.S. Congress authorized funds 

for construction of the first permanent post office in 

Grand Junction, Colorado. The building was 

originally completed in 1918 at a cost of $250,000 

and was designed by then-Supervising Architect of 

the Treasury, James Wetmore. Modifications were 

made by Wetmore’s successor, Louis Simon. 

The building is a rectangular steel and concrete 

structure with a limestone façade and parapet 

balustrade. The original design incorporated a 

second and third floor light well in the rear of the 

building. The dominant features of the building are 

the arched first-floor windows with sidelights, 

broad granite steps, and arcaded windows with 

carved capitals. The building is architecturally significant as an example of the Second Renaissance 

Revival-style government building.

The building has undergone major changes during its lifetime. As new agencies began leasing space 

within the building, spaces were converted to fit the needs of the tenant agencies. The result was a 

conversion of the prominent public spaces into new office space, as commonly occurs with historic 

buildings: occupancy needs change, over time. 

An expansion of the building to the east, as part of the Works Project Administration, was completed in 

1938. In the mid 1960’s, the U.S. Postal Service moved out of the building into an adjacent free standing 

structure, and GSA took possession of the building, leasing out the available space created by the U.S. 

Postal Service to other Federal agencies. Today, the total floor area of the building is nearly 42,000 square 

feet, although only 21,000 square feet are occupied. 

During the course of decades of modifications, the public lobby, which once spanned most of the length 

of the south façade (nearly 40 feet from the elevator to the historic southwest staircase), was reduced to a 

modest 15-foot ×15-foot entry vestibule. A decision to locate office space along the perimeter of the 

building’s first floor resulted in small corridors that were cut off from natural daylight, and inhibited 

overall traffic flow.

 

13 The Aspinall Courthouse is listed as the U.S. Post Office at 400 Rood Ave, Grand Junction, CO on the National 

Register of Historic Places. Accessed February 26, 2014: http://www.nps.gov/nr/research/. 
10 

Figure 5. Aspinall Courthouse light well in the 

rear of the building, circa 2012

Source: GSA

The original building design did not include 

HVAC systems. An HVAC system was 

introduced into the building in the 1960s, along 

with upgraded electrical systems. Dropped 

acoustic ceiling tiles were installed to mask the 

new ductwork, lowering the ceiling height and 

reducing the volume of internal airflow. The 

original lighting fixtures were replaced with 

ceiling-mounted fixtures and wall sconces. 

In 1972, the building was rededicated. It was 

named the Wayne N. Aspinall Federal Building 

and United States Courthouse, after Democratic 

Congressman Wayne N. Aspinall, who served in 

the U.S. House of Representatives from 1949–

1973 and hailed from Colorado’s Western Slope. 

In 1980, the Aspinall building was listed on the 

National Register of Historic Places. The building currently hosts offices and courthouses for U.S. Courts, 

U.S. Probation, U.S. Marshals, the U.S. Army Corps of Engineers, one of Colorado’s state Senators, the 

Federal Bureau of Investigation, U.S. Attorneys, the Internal Revenue Service, and GSA.

In 2010, GSA considered disposing of the property because the building needed extensive repairs and 

renovation that GSA could not hope to cover from existing or expected appropriations. As a 1918 

building with almost 42,000 square feet of office space, the Aspinall Courthouse needed major updates 

and repairs to address a long list of deficiencies, including poor lighting, windows that had been covered 

up, low-hanging ceilings, and poor ventilation and indoor air quality. 

Many of the building’s significant systems had reached the end of their useful life, notably, the

mechanical and electrical systems, the elevators, and the roofing materials. If GSA were to renovate the 

building, it would have to ensure, at a minimum, upgrades or replacements for these critical systems. 

Because the building had been listed on the National Register of Historic Places, the modernization would 

have to comply with Section 106 of the NHPA of 1966 for rehabilitation of historic structures, as

described in Section 1.2 of this summary. Section 106 of the NHPA requires Federal agencies to assess 

the effects of their undertakings on historic properties and to provide the Advisory Council on Historic 

Preservation with the opportunity to comment on such undertakings, if there is a potential to affect 

historic properties. GSA considered disposal of the historic property. 

Disposal was averted when Congress enacted ARRA, appropriating funding for real property upgrades 

that ultimately enabled GSA was able to keep the Aspinall Courthouse from closing its doors. Instead of 

preparing for disposal of the building, GSA began to outline an unprecedented plan to carry out an 

extensive renovation project combining net-zero energy and historic renovation goals. Uniquely, in this 

single but significant undertaking, GSA was doing its part to preserve the future by restoring the past.

The GSA used ARRA funding to reduce energy consumption and incorporate sustainable design into 

projects on a national scale. A variety of contracting mechanisms were used to complete these projects, 

but for the Aspinall renovation, GSA chose a design-build contract, which is discussed in a following 

section. The design-build goals of the renovation centered on full mechanical, electrical, and plumbing 

replacement and used a life cycle cost analysis with a goal of reaching 30% better performance than 

ASHRAE Standard 90.1-1999. The project budget totaled $15 million in ARRA funding and included 
11 

design build, construction management and commissioning agent.

14 The cost of the renovation was about 

$360/ft2

. All implemented net-zero energy measures had a positive life cycle cost.

2.2 Project Goals

GSA’s Minimum Performance Criteria for Recovery Projects for new construction and major renovations 

set parameters to comply with the Guiding Principles15 as well as third-party green building certification 

requirements. GSA identified renovation goals for the Aspinall Courthouse, which centered on 

sustainability principles and energy use. Aware that the renovation had to comply with historic 

preservation standards as well as meet net-zero energy goals, GSA established the following list of 

objectives for the renovation:

1. Realization of a net ZEB (aligning with government requirements for net-zero and energy 

independence by 2030)

2. U.S. Green Building Council Leadership in Leadership in Energy and Environmental Design 

“Platinum” certification

3. Improved indoor environmental quality and thermal comfort

4. Water use reduction (~40%) 

5. Use of sustainable construction practices

6. Effective use of technology while preserving historic attributes of the building. 

The sixth objective was crucial to the success of the historic renovation because, paradoxically, the key to 

historic preservation was careful integration of innovative technology with principles of sustainable 

design. In service to this objective, GSA decided to focus the Aspinall Courthouse renovation on 

preserving specific architectural elements of the building and re-establishing formerly prominent 

architectural features and spatial relationships, to ensure full adherence to the Secretary’s Standards. 

 

14 Design-build is a construction industry method used to deliver a project using a single point of responsibility 

contract to minimize risks for the project owner and reduce the schedule of a project. 

15 http://www.wbdg.org/sustainableEO
12 

3 Aspinall Courthouse Renovation Process

The success of the Aspinall Courthouse renovation is due, in part, to the foresight of the planning team, 

which established its goals early in the process. This section details that process and the goals achieved. 

3.1 Design-Build Contracting

The unique combination of net-zero design considerations with historic preservation goals required an 

extensive and ongoing planning and problem-solving process during the design stage. GSA selected and 

applied a design-build process,

16 targeting net-zero performance first. Although historic preservation 

would be addressed specifically during the NHPA Section 106 review process, GSA’s planning team had 

to consider in the design phase how the project would comply with the Secretary’s Standards in order to 

ensure a successful outcome during Section 106 review. 

3.1.1 Selecting a Design Team

Selecting a team for a renovation project with net-zero and historic preservation goals is the most 

important upfront decision. Essential to success is a team that identifies goals, develops and demonstrates 

an effective strategy to achieve those goals, can review critical points of the design process, and 

ultimately reaches the identified goals.

Typically, for government construction projects, the first steps are a request for qualifications and a 

request for proposals. A request for qualifications is an opportunity for the building owner and project 

lead to request specific qualifications from design-build teams. The Aspinall Courthouse renovation 

followed the two-step procurement process consisting of a request for qualifications and a request for 

proposals stage. The proposal phase required bidders to address minimum performance criteria and 

encouraged bidders to provide innovative design options to expand on energy goals. Bidders were invited 

to suggest ways in which modern, high-performing technologies could be integrated into the historic 

structure. 

The design-build contract offered benefits to a project focused on energy enhancements by integrating the 

entire project team at the outset of the project. Early design meetings were structured to ensure the 

presence of the owner, builder, architects, engineers, commissioning agent, and construction manager

during this critical phase of project development. It was during these meetings that the team was able to 

establish net-zero energy and historic preservation goals for the project. 

3.1.2 Identifying Risks

The team identified risks to each party at the start of the project and throughout its execution. For 

instance, shared risk among all participants ensured accountability for goal achievement. The contractor 

bore risks of its acceptance of a firm-fixed price contract based on a program of requirements, scope of 

work, agency design guidelines, policies and the design-build proposal. The risks to the design-builder 

related to the uncertainty presented by the innovative renovation project, where the contract required the 

design-builder to maintain pricing through design development based on the contract documents and 

through construction. For GSA’s part, as the owner, it bore the risk that the conceptual design (which had 

been proposed at time of award) could be altered significantly if the NHPA Section 106 historic 

preservation reviews were not favorable. 

 

16 Design-build is a construction process that allows the design and construction services to be contracted by a single 

entity, often simplifying contractual obligations and expediting the construction process. 
13 

Significant to the aggressive energy goals set by the planning team was the additional risk that decisions 

of the SHPO, Grand Junction Historic Preservation Board, and the ACHP could adversely affect the 

Aspinall Courthouse’s energy performance. The project’s design direction sprang from the design-build 

proposal, and the historic preservation reviews could only take place post-award. Therefore, ongoing

discrete changes to the design could occur mid-project through change order requests with the contractor, 

and cumulatively could compromise the general design intent, including its energy and sustainability 

goals. Finally, an overarching challenge to the entire team was undertaking a construction project in an 

occupied historic building, where construction crews could encounter unforeseen conditions and potential 

schedule impacts. 

In light of the unusual risks presented by the Aspinall project, early collaboration was essential. Overall, 

the design-build approach supported collaboration among entire project team, enabling it to consider

problems and solutions, and identify opportunities that may not otherwise have emerged. The integrated 

team approach enhanced the project’s energy and preservation goals. In retrospect, the design-build

contracting method conferred significant advantages on this unique and significant project, allowing

broader than average reviews of systems, constructability, cost benefits and improved energy 

performance, and perhaps above all, the exchange of ideas that elevated common interests over the 

positions of the parties. 

3.2 Principles of Net-Zero Design and Operations

For any structure to achieve net-zero, energy loads must be analyzed and minimized. A building’s energy 

use is typically determined by four main systems: HVAC, lighting; the building envelope, and plug loads. 

As such, the design process involved four steps: 

1. Optimize the building envelope. 

2. Reduce internal loads. 

3. Design high-efficiency systems. 

4. Match building energy load to on-site renewable energy. 

Extensive energy modeling is typically conducted to analyze the impacts of various measures on a 

building’s energy performance. Modelers develop the geometry of the building, import weather data for 

the location of the building, assign equipment types and efficiencies, and then develop various scenarios 

relating to modifications within building systems. For example, modelers may analyze the impacts of 

different lighting systems or plug loads, adding specific types of insulation (and assigning different Rvalues), different window systems (and assigning different U-values), and/or installing renewable energy 

systems. The development of various scenarios allowed the design team to determine the best strategies 

for minimizing energy loads within the project’s parameters. In the case of the Aspinall Courthouse, 

historic preservation strategies influenced energy strategies. 

The energy modelers for the Aspinall Courthouse used a 10-year weather average for Grand Junction and 

included plug load data from the building’s occupants pre-construction. The model included optimal 

system performance criteria, such as indoor set points of 75°F for cooling, 69°F for heating, set hours for 

operation, averaged hours of direct sunlight, and impact of lighting system design. Table 1 shows the 

modeled energy consumption compared to energy production. The modeled performance illustrates how a 

building can accomplish net-zero energy use: over the course of a year, the building’s renewable energy 

systems can produce more energy than the building consumes annually. An example of the model 

rendering is shown in Figure 6.
14 

Table 1. Modeled Monthly Energy Consumption and Production

Estimated 

Monthly 

Electricity

Consumption 

(kWh)

PV Production 

Monthly Total 

(kWh)

Total Production 

Beyond 

Estimated Use 

(kWh)

January 13,998 7,998 –6,000

February 11,371 10,139 –1,232

March 12,063 14,504 +2,441

April 10,853 17,504 +6,651

May 13,804 20,559 +6,755

June 16,577 21,414 +4,837

July 17,270 20,445 +3,175

August 17,571 18,813 +1,242

September 14,235 15,461 +1,226

October 12,342 11,995 –347

November 12,195 8,296 –3,899

December 13,277 6,809 –6,468

Annual Totals 165,556 kWh 173,897 kWh +8,381 kWh

Figure 6. A modeled rendering of the Aspinall Courthouse façade

Source: Jimmy Salasovich, NREL

Constructing a building designed for net-zero energy consumption is just the first step. After construction, 

even the most energy-efficient building can waste plenty of energy if it is not operated efficiently. 

Efficient operations include monitoring and verification (M&V), which is key to realization of net-zero 

energy goals. 

Usually, in the absence of a cohesive, effective net-zero operations plan that includes M&V, energy goals 

can be lost as systems are pieced together through negotiations with contractors, manufacturers, and 

operations managers. M&V principally includes comprehensive monitoring of the building systems, 

established energy consumption targets and data collection, and defined roles and responsibilities of 

facility managers. 
15 

Two factors are key to a successful M&V plan: 

(1) the owner must have an active role in energy 

performance; and (2) the project delivery team 

must retain a strong role during postcommissioning through the first year of the 

building’s operation. Building operators may 

require training in using monitoring programs 

and building systems. Interaction with and 

obtaining feedback from occupants is important 

to determine where system operations need to be 

modified or fine-tuned. An effective net-zero 

operations plan includes the following steps and 

considerations to ensure net-zero energy goals are 

met and maintained:

• Identify key energy decision-makers in 

the facility and list them in the plan, 

along with their roles and 

responsibilities. 

• Ensure the design and construction process delivers a useful expectation/prediction of absolute 

energy use. 

• Use warranties, commissioning, and/or incentive programs to address efficiency-related 

strategies. 

• Utilize funding streams, such as utility rebate funds, to reinvest in implementing new (and 

enhancing existing) efficiency-related strategies. 

• Educate building operators on efficiency strategies. 

• Implement strategies to address: glare from natural daylighting, lighting adjustments, plug load 

selection and operations, data center performance tracking, useful metering for real-time end-use 

budget tracking, HVAC controls and sequence of operations, night and weekend load 

management, new loads or occupant systems management, etc.

• Evaluate performance and assess goals, then modify strategies to improve efficiency and add 

renewable energy technologies, where needed. Scheduling regular strategic meetings will assist in 

keeping this evaluation on track.

• Occupant engagement and education, public relations and tours. 

3.3 Implementation of Renovation Measures

The Aspinall Courthouse renovation project established the goal of becoming GSA’s first net ZEB on the 

National Register of Historic Places. The Aspinall Courthouse renovation consisted of no fewer than 12 

separate renovation measures. Some measures were conducted to improve the energy performance of the 

building, some measures were intended to restore historic architectural features, and some measures 

addressed both areas. The energy efficiency and net-zero energy features were designed to meet 

Leadership in Energy & Environmental Design Platinum certification (http://www.usgbc.org/certguide/commercial) while historic spaces and finishes within the public and agency areas were restored. 

3.4 Historical Measures

Often, with historic properties, the original features have been covered by previous renovation projects, 

only to be revealed in future work. In 1965, the U.S. Postal Service vacated the Aspinall Courthouse 

Measures by the Numbers

Total Renovation Cost: $15 million

Cost per square foot: $360

The design team’s approach to energy 

savings and historic preservation resulted 

in a projected reduction in energy use of 

68% compared to Standard 90.1-2007 

Design Building.

The solar PV panels are anticipated to 

produce more than 173,000 kWh/year, 

which provides a net energy savings 

annually. 

The building is anticipated to save 40% on 

water consumption and have a carbon 

footprint of 5.6lb CO2e/ft2/year. 
16 

Figure 8. Lobby pre-construction (2010)

Source: GSA

Figure 7. Lobby in 1938

Source: GSA

building; GSA, after taking ownership of the building, modified the two main entrances, first-floor post 

office area, and elevator lobbies for the building tenants. 

During the ARRA-funded renovation project, some of the renovation measures restored the courthouse’s

original historic features and spatial relationships, while improving efficiency. One such measure was the 

removal of the false ceilings that had been installed; this restored the original spatial relationship between 

the tenants and the building and enabled the full advantage of the building’s original passive lighting 

features. 

The net-zero energy renovation project restored many of the Aspinall Courthouse’s original features: 

• The main lobby was extended from the small 

entry vestibule to its original size. 

• The three-floor height historic curved 

stairwell was reconnected with the lobby. 

• Original arched windows, interior arched 

colonnade, decorative column capitals, 

marble-bordered terrazzo floor, and other 

historic elements were re-exposed to be 

visible from the lobby. 

• Wood features were restored, such as the

flooring in the lobbies and corridors, and the 

original wood paneled doors. 

• Arched windows that were hidden behind 

dropped ceilings were revealed again. 

• Original doors, walls, and ceilings were 

repaired and refinished. 

• The original skylight in the post office 

workroom was restored to provide increased 

daylight. 

By repairing and refinishing the existing doors, walls, 

and ceilings, the project team was able to reduce the 

amount of project waste, avoiding hauling, demolition 

and landfill costs that would be incurred in conventional 

renovation projects. 

3.4.1 Efficiency Measures

Preserving historic features can have a positive 

environmental impact. For example, reusing an existing 

building extends the life of the resources that were used 

to construct the building in the first place, and reduces 

demolition waste. For Aspinall, all the measures that 

relate specifically to energy efficiency or the overall netzero energy design of the building were considered with 
17 

Figure 9. 123-kW PV roof-mounted system

Source: Kevin Reeves, GSA, 2013

historic preservation in mind. However, as one might expect, not all energy savings measures could be 

completely isolated from the historic preservation features of the project. The design team took special 

care with their incorporation into the renovation design. 

Energy efficiency measures included: 

Building Envelope

• Installing spray foam insulation (with a thermal resistance of R-10) to the masonry walls, 

reducing overall building energy consumption by 11%.

• Installing 10-in. rigid insulation on the roof (average thermal resistance of R-35), to reduce heat 

loss and heat gain. Reducing heat loss and heat gain led to down-sizing the heating and cooling 

equipment compared to the pre-renovation system sizes, which is more efficient, reduces the use 

of ozone-depleting refrigerants and saves on installation and operational costs. 

• Adding a white colored roof membrane, also 

called a ‘cool roof’, to reduce solar gain and 

air-conditioning loads. Cool roofs are thought 

to reduce urban heat island effects and reduce 

air conditioning needs.17

• In order to preserve the historic wood-framed, 

single-paned windows, the project team 

installed new storm panels with highperformance UV control film in lieu of doublepaned replacement windows. This measure 

reduced the U-value from 1.04 to 0.5, and the 

solar heat gain coefficient from 0.86 to 0.53. 

Electrical and Mechanical Systems

• Replacing outdated mechanical and electrical 

systems with highly efficient technologies, including a water-source variable refrigerant flow 

HVAC system (which reduced the need for ozone-depleting refrigerants). 

• Replacing inefficient lighting systems with LED systems or T-8 lighting to reduce energy 

consumption, cooling load, and maintenance.

• Installing advanced metering and wireless controls for lighting and HVAC system control, 

including solar powered devices, which reduce the need for wiring, thus reducing the impact to 

the historic structure. Workstations are located close to windows for natural daylighting. 

• Perimeter light fixtures have been zoned separately and equipped with dimmable controls to dim 

or switch off electric lights as natural daylight increases, thus preventing overlit areas and saving 

energy. 

• Pairing the high-efficiency HVAC system with a geothermal exchange system to filter and 

condition air for comfortable cooling and heating year-round. (See geothermal exchange system 

under clean energy solutions). 

 

17 DOE states that a cool roof can reduce a single story building’s air conditioning use by 15%; 

http://energy.gov/sites/prod/files/guide_to_cool_roofs.pdf 
18 

Figure 10. Aspinall Courthouse, north elevation, postconstruction 2013

Source: Kevin Reeves, GSA

Water Systems 

• Replacing high-volume plumbing fixtures with low-flow, EPA WaterSense rated plumbing 

fixtures, which are estimated to reduce water use by approximately 40% less than a typical 

building. 

Clean Energy Solutions

• Installing a solar photovoltaic canopy on the roof (385 panels generating 123 kW of electricity) to 

produce an estimated 173,897 kWh per year.

18 

• Installing a geothermal exchange system (with 32 ground-source wells, at 475 feet deep) to allow 

the building to reject heat into the ground during the warm months or absorb heat from the 

ground in the cooler months. This system is called a geothermal exchange system because it 

provides both cooling and heating using stable ground temperatures throughout the year. 

Alternative Transportation Modes

• Fuel-efficient vehicle parking spaces have been designated and a bicycle rack installed to 

encourage alternative modes of transportation that reduce fuel use.

3.4.2 When Old Meets New 

The Aspinall Courthouse renovation is 

an example of modifying historic 

buildings to improve energy 

performance, without impacting the 

historical integrity of the building 

structure. The following examples of 

measures that include introducing new 

technology while maintaining the 

historic features highlight the success 

of the Aspinall Courthouse project. 

Building Envelope Improvements

The design team discerned an 

innovative way to increase the R-value 

of the building envelope without 

damaging the integrity of historic 

plaster walls and window casings. The 

team took a thermal infrared image of 

the building early in the project to determine where heat was being transmitted through the building 

envelope. The team visually noted heat loss through the building’s leaky envelope, and determined that a 

viable measure to reduce heat loss was to increase the R-value of the walls. The walls, as mentioned 

previously, are comprised of an exterior limestone façade, backed with a terra cotta block, metal lath, and 

an interior plaster wall finish. Changing the plane of the interior plaster would negatively impact other 

historical components of the interior, such as window casings. The design team decided to remove the 

plaster wall, metal lath, and the terra cotta block to create a wall cavity that could be filled with 2” of 

spray foam insulation throughout the building’s perimeter to increase the R-value of the wall to R-10. An 

analysis for dew point changes was conducted to determine whether an increase in dewpoint would occur, 

causing condensate and mold issues. The team determined the changes to be negligent, so the measure 

was completed, saving 11% in energy. 

 

18 Based on 385 panels rated at 320W each (SunPower E19 modules).
19 

Figure 11. Lobby post-construction 

in 2013

Source: Kevin Reeves, GSA

The following table illustrates the baseline design of the Aspinall Courthouse compared to the proposed 

design for improved efficiency. The proposed case shows the modeled energy performance. Windows are 

not included in the table, but had a final U-value of 0.5, a solar heat gain coefficient of 0.53 and a 45% 

visual transmittance. 

Table 2. Baseline Versus Proposed Design Elements 

Model Input 

Parameter or 

Energy 

Efficiency

Measure 

Baseline Case Proposed Case 

(Improved Efficiency)

Description Insulation RValue 

Assembly

U-Factor/

C-Factor/

F-Factor

Description Insulation RValue 

Assembly

U-Factor/

C-Factor/

F-Factor

Roofs Insulation above 

deck (exist) R-15 0.06 Insulation above deck R-35 0.03 

Roof SRI Membrane 

(exist), SRI = 30 

TPO 

membrane, 

SRC=78 

Walls Above 

Grade Existing masonry None 0.183 Existing + 2-in. spray foam R-13 0.075 

Walls Below 

Grade Existing masonry None 0.259 Existing + 2-in. spray foam R-13 0.075 

Slab-onGrade Floors Existing masonry None F-0.73 Existing 

masonry 

None F-0.73 

Opaque 

Doors Swinging U-0.7 Swinging U-0.7 

A High-Efficiency HVAC System

The design team chose the variable refrigerant flow (VRF) 

fan coil system was chosen for the project because for it is 

both highly efficient and because it requires minimal 

ductwork, which meant fewer intrusions into the historic 

design of the building. In the water-based system, the fan 

coils are connected to the geothermal heat pump system. 

The variable flow system allows greater energy savings than 

a traditional fixed-flow system because the system can ramp 

up or down depending on the season and occupancy 

demands. The heat pump rejects heat through the water 

source or absorbs heat from the ground. The vertical 

geothermal wells are located in the parking areas and city 

alleyways adjacent to the building.19 The system overall is 

far more efficient than typical HVAC systems (geothermal 

heat pumps and exchange systems are typically 45% more 

efficient than traditional HVAC systems) and reduced the 

visual impact on the historic features of the building. 20

 

19 The City of Grand Junction provided the alley space for 12 of the 32 wells due to the building’s existing site 

constraints.

20 www.energystar.gov/products/certified-products/detail/heat-pumps-geothermal 
20 

Figure 12. Tenant space

pre-construction, 2010

Source: Kevin Reeves, GSA

Figure 13. Tenant space postconstruction, 2013

Source: GSA

Efficient Lighting

The historic exterior stair lights and the wagon wheel bronze fixtures in the courtroom were the only 

remaining lights from the 1938 renovation. These fixtures were re-lamped with LED lamps, reducing 

energy consumption as well as cooling loads and reducing fixture maintenance. The lobby lighting was 

recreated using the 1918 teardrop light fixtures as inspiration, as shown in Figure 11. These lighting 

fixtures, along with all of the building’s lighting fixtures within 15 feet of the windows, apply daylighting 

controls. 

Controls and Metering

The building renovation incorporated advanced metering to allow real-time energy and water use 

monitoring, which helps inform those who manage the building’s utility costs. These data support

decision-making processes and make instantaneous control of building systems for optimum performance

possible. 

Newly installed occupancy and daylight sensors ensure that no energy is wasted lighting unoccupied 

spaces. The majority of these are wireless to minimize intrusion on historic plaster walls and ceilings. 

Additionally, many of the wireless controls are solar powered, reducing energy consumption even more. 

Daylight sensors dim and turn off lighting fixtures installed near windows when the light levels are 

adequate from natural daylight. In common areas lighting switches on manually, but turns off 

automatically, after a designated amount of time. Occupants may also turn lights off manually. Lighting 

in public spaces is set to 1 footcandle for safety lighting, when the space it not occupied from 6:00 a.m. to 

6:00 p.m. After 6:00 p.m., public space lighting automatically switches off if sensors do not detect 

occupancy. 

In the Aspinall building, many aspects of lighting and HVAC are driven by automatic detection of 

building occupancy. The same wireless controls that detect occupancy to regulate lighting are connected 

to the HVAC systems, which also detect CO2 levels. An outside air monitoring unit provides fresh air to 

the building depending on the indoor CO2 levels, which increase with occupancy. Each tenant space is 
21 

zoned separately, permitting greater occupancy-driven control over conditioning of spaces, as well as by 

activities specific to tenants. Energy and water consumption data is gathered, stored and displayed for the 

entire building. The before-and-after images in Figures 12 and 13 illustrate the use of natural daylight and 

more efficient lighting fixtures in the tenant spaces. 

To better manage plug loads, the project team incorporated two measures. Each cubicle is equipped with 

desk-mounted occupancy sensors wired to smart plug strips, which power down equipment after the 

workstation becomes “inactive”. Certain plugs in the strips can be used for equipment that needs to stay 

on at all times, enabling the occupant to control his or her power needs. The second measure is the 

installation of a load shedding device in many convenience outlets throughout the building. The load 

shedding device is scheduled to turn on in the mornings and off in the evenings and over the weekends. 

These devices eliminate phantom power or ghost loads from equipment plugged into them. A green 

sticker affixed to the outlets indicates which are equipped with the load shedding devices. 

3.5 Innovative Solutions

The project team encountered a number of challenges during the design, modeling, and execution of the 

renovation project. The challenges are identified in this case study to illustrate what may be common 

problems in future similar projects, and the ways GSA and the design-build team were able to overcome 

them. Alignment of the net-zero operations goal and historic preservation requirements were addressed 

and the alignment process was based largely on negotiations with the SHPO. The GSA Center for 

Historic Building provided feedback, as well. The largest change resulting from the NHPA Section 106 

review process was the modification of the PV system design.

3.5.1 Solar PV 

In order to accommodate the Secretary’s Standards, the project team designed the PV canopy as an 

“additive” structure so that it could be removed without adverse impact to the property after 25 years, 

when the panels either reached the end of their useful life or the advancements in PV technology had 

increased efficiency to the point that less surface area would be required to produce the same amount of 

energy (i.e., a smaller system could be installed to produce the same amount of energy). This design 

accommodated the principle of the Secretary’s Standards requiring preservation of the essential form and 

integrity of the historic property upon removal of additional or adjacent structures. 

However, during the NHPA Section 106 review, another of the Secretary’s Standards threatened to 

compromise the energy goals of the project. The requirement that exterior alterations be compatible with 

the historic nature of the property and not...“destroy historic...features and spatial relationships that 

characterize the property” became a challenge in consideration of the PV canopy, which would be visible 

from the street. The NHPA reviewers requested that the project team reduce or remove the PV canopy 

from the Aspinall Courthouse. 

Removal of the PV canopy would have been a serious impediment to the net-zero energy goals of the 

renovation design, since the building would have to produce energy to offset its energy use over the 

course of a year. Chiefly, the reviewers faulted the design because it was visible from the street. The 

project team was able to redesign the PV canopy to completely eliminate its visual impact along a) the 

south façade and directly across the street, and b) the east and west sides of the building from the

sidewalk level adjacent to the building. This tactic of reducing visual impact has become a common 

approach for meeting requirements of historic preservation while integrating newer technologies.

21 

 

21 Kandt A; Hotchkiss, E; Walker, A.; Buddenborg, J.; Lindberg, J (2011). Implementing Solar PV Projects on 

Historic Buildings and in Historic Districts. NREL/TP-7A40-51297, Golden, CO: National Renewable Energy 

Laboratory. 
22 

The smaller PV canopy affected the energy aspects of the overall renovation design. The alteration

reduced the PV system from 170 kW to 123 kW (a 35% reduction). This had an impact on the overall 

energy generation system that required the design team to incorporate additional energy efficiency 

measures to reduce energy demand. The additional measures included several deep retrofit measures and 

two additional geothermal heat pumps. The geothermal exchange system was not in the original design, 

but was added to accommodate the smaller PV canopy that resulted from the AHCP Section 106 review 

process, helping the project team reach net-zero energy goals. 

3.5.2 Ground-Source Exchange System

The geothermal exchange system utilizes the consistent temperature of the earth to provide heating, 

cooling and hot water. The 475-foot vertical wells allow the building to reject heat into the ground or 

absorb heat from the ground depending on the time of year and the demand for heating or cooling. 

Because the ground is relatively constant at 64°F throughout the year, the HVAC and water system only 

need to alter the temperature a few degrees to condition the indoor space and heat water. As mentioned 

previously, geothermal exchange systems are approximately 45% more efficient than typical HVAC 

systems. 

Energy Modeling

As challenges arose and the design team selected new building technologies to meet net-zero energy 

goals, energy models were modified. The design team altered the original energy model to include the

new design scenarios. For example, after the historical review process resulted in a compromise to reduce

the solar PV system size, the the estimated expected total project energy savings needed to be made up 

using the ground-source exchange system. 

Figures 14 and 15 show the comparison between the modeled energy end-use and actual post occupancy 

metered energy use. The pie chart in Figure 14 shows the modeled end-use electrical consumption for the 

Aspinall Courthouse. Figure 15 shows the actual energy end use breakdown in February 2014. The model 

uses the constructed project and estimated tenant loads, whereas the actual end-use shows the data from 

metered equipment and systems in the completed building, post-occupancy. An example is the heating 

and cooling being generalized in the model, but being broken out into heat pump, variable refrigerant 

flow, and dedicated outdoor air supply (DOAS) in the actual data. Unregulated loads are those that lie 

within the tenant spaces, such as plug loads. 

Conducting energy modeling frequently and updating models that simulate the measures needed to 

achieve net-zero energy goals, along with regular team reviews of the models, is essential to make 

informed construction and goal-making decisions. By modeling the reduction in PV and adding the 

geothermal exchange system, the project team could see whether net-zero energy goals would be 

achieved. The results from energy modeling are also useful to compare to actual consumption after 

building occupants have begun to use the building in its renovated state. The comparison informs 

improvements in future modeling and provides an assessment that may indicate systems that may need to 

be commissioned or modified to improve energy savings. 
23 

Figure 14. Modeled end-use electrical consumption in the Aspinall Courthouse

Figure 15. Actual end-use electrical consumption as of February 2014

3.6 Commissioning Operations

Commissioning is necessary in order for a building to achieve optimal performance. The Aspinall 

Courthouse follows a GSA Net-Zero Energy Management Plan, which includes requirements for 

reviewing the Building Management System for efficient operation. The plan includes steps related to 

commissioning and management of the building that apply to GSA staff or to contracted O&M. 

Heating, 9%

Cooling, 

14%

Lighting, 15%

Fans, 22%

Pumps, 1%

Hot Water 

and Elevator, 

2%

Unregulated 

Loads, 37%

VRF, 39%

Heat Pump, 

3%

DOAS, 2%

Lighting, 

13%

Fans, 2%

Pumps, 8%

Hot Water 

and Elevator, 

2%

Unregulated 

Loads, 31%
24 

Commissioning of the building following a renovation is crucial to determine whether systems are 

performing as designed and installed. During commissioning, each building system needs is tested and 

monitored to determine how it is performing and to troubleshoot any systems that are underperforming. 

Facility energy managers should take the measures identified in the commissioning report to optimize the 

building systems. A thorough commissioning process will incorporate monitoring of tenant use and 

behavior, as an element of determining whether facility managers are operating building systems to 

support building functions adequately. The net-zero management team will need to monitor all of these 

facets to ensure the building meets its energy performance potential, given its size, design and function. 

The Aspinall Courthouse renovation project included a separate contract for one year following 

renovation completion to support data collection and analysis, identification of anomalies in energy 

consumption and solutions for addressing anomalies. The design-build and net-zero management team 

held weekly meetings to review and correct building system operation to review assumptions made in the 

energy model (based on construction documents from August 2011). 

The project team focused on building performance and ensured the Aspinall Courthouse was within 5% 

of its net-zero operations goal. The contractual goal was to ensure that the building systems installed 

under the contract operate at, or below, the estimated energy use gathered from the product literature and 

energy model. The tenant plug loads, however, were not included in this contract requirement since that 

was outside of the contractor’s control, which is one reason they are modeled and metered as ‘unregulated 

loads’. Contractual compliance through performance assurance focused on installed systems performing 

within a total of 5%. One full year of enhanced M&V is necessary to review systems in each season and 

make adjustments as necessary. 

The team approached commissioning of the building systems in a three-step process. First, the energy 

model estimates were compared with actual energy use from monitored data. Next, if the total energy use 

was greater than the modeled use, the equipment was adjusted. Lastly, the monitored data collected after 

the adjustment was compared to the modeled data to determine if the adjustment had corrected the energy 

consumption of the system. The last two steps were repeated until the equipment functioned at the highest 

possible efficiency.22 

Often, optimization of systems during commissioning requires simultaneous adjustments of other 

building systems to ensure that energy savings accomplished by one system do not correspondingly

increase the energy use of another system. The building systems were broken into different categories 

(lighting, hot water, the elevator, variable refrigerant flow, dedicated outdoor air system, etc.), and the 

project team systematically optimized each of the systems individually, and then as a whole. This system 

commissioning approach was effective for the Aspinall Courthouse and could be replicated to achieve 

savings. 

A specific example of the beneficial impact of M&V included in the Aspinall Courthouse postcommissioning operations lies within the geothermal system. The team found that the geothermal 

exchange system was using excessive amounts of energy. Further investigation led to the discovery that 

while the two pumps were designed to operate alternately, they were operating simultaneously. Once the 

pumps were reprogrammed, the energy consumption of the system aligned with the modeled energy data. 

Another measure implemented during post-commissioning was the establishment of set-points for the 

building. The set-points were different than what many occupants in the building had become accustomed 

 

22 For more information on the various types of commissioning see DOE EERE’s O&M Guide, Section 7.2: 

www1.eere.energy.gov/femp/pdfs/OM_7.pdf. 
25 

to, and ranged from 72°F to 75°F year-round. These set-points fall within the ASHRAE 55 Comfort 

Conditions standards for office buildings,

23 as well as the Public Building Services P10024; however, it 

was important for the project team to reduce energy even further by adjusting the set-points. The team 

worked to educate tenants and adjust temperatures to a higher range in the summer (75-78°F) and a cooler 

range in the winter (69-72°F), allowing for more significant energy savings in the building. 

The category of unregulated loads includes plug loads, as shown previously in Figure 15, which are 

estimated to be 35,000 kWh higher than the annual target for unregulated loads. As a result of the 

building’s overall envelope improvements and system upgrades, plug loads become the largest consumer 

category. GSA is working with tenant agencies to address plug loads as a separate, ongoing goal of 

reaching net-zero operations. GSA distributed a Tenant Guide as part of the occupant engagement 

strategy, which describes the installed systems, energy goals of each agency and ways in which occupants 

can address plug loads. Tenant agencies meet monthly to review plug load data, as well as Federal

requirements for energy efficient office equipment procurement as a way to reduce plug load energy 

consumption. 

All of the post commissioning operations are analyzed and compared. The energy use intensity 

comparison is a helpful exercise to undertake (shown in Figure 16) during post commissioning to review 

the targets and the actual performance of the building. The original target and calibrated target are from 

modeled data, whereas the 12-month gross is the actual energy consumption in the building. The 12-

month net data show the energy performance after commissioning; the PV system further reduces the onsite consumption. Renewable energy credits further move the goal to zero energy consumed. The plug 

load contribution was isolated to determine how much of an impact tenant control over their leased spaces 

has on the energy consumption of the building. The Aspinall Courthouse team included comparisons of 

median and Energy Star 100 buildings to benchmark the renovation improvements in energy 

consumption. 

 

23 ASHRAE Standard 55-2013 Thermal Environmental Conditions for Human Occupancy available at 

https://www.ashrae.org/news/2013/ashrae-publishes-2013-version-of-thermal-comfort-standard 24 Public Building Services P100 is a GSA facilities standard establishing design standards and criteria for new 

buildings and renovations. More information is on the GSA website at www.gsa.gov/p100. 
26 

Figure 16. Energy use intensity comparison (March 2013–February 2014)

While some benefits of the renovation project can be measured, others are only qualitative. Quantitative 

benefits include reduced utility costs, reduced operations and maintenance expenditures, less frequent 

equipment replacement due to longer life-times, fewer work orders generated by occupant comfort 

complaints, lower absentee rate and staff turnover due to more comfortable working conditions, improved 

safety record, less overtime for maintenance staff, reduced backlog of preventive and reactive 

maintenance items. The qualitative benefits, some of which could be measured, but are not being 

measured by GSA, include reduced environmental impact of operations, public relations value for 

improved sustainability, greater thermal comfort, improved indoor air quality, reduced noise, better 

lighting quality, increased productivity and the flexibility to accommodate future changes to the building. 
27 

4 Lessons Learned

The Aspinall Courthouse historic preservation and net-zero renovation is a prime example of potentially

sweeping energy improvements in an existing Federal historic building. The project represents an 

unwavering commitment to historic preservation and sustainability. The renovation project set goals for 

energy efficiency and historic preservation while improving the indoor environmental quality to improve 

health and productivity for the building’s occupants. The design-build approach acknowledged the federal 

government’s goal to be carbon-neutral by 2030 and to create, through this project’s design, a “green 

proving ground” demonstrating how to potentially make an existing historic building perform at net-zero 

energy, 17 years ahead of schedule.25 

While the net-zero energy goals will not be realized 

until a full year’s worth of energy consumption and 

production data have been obtained, the building has 

won many accolades and praise for successfully

implementing energy efficiency measures, 

implementing far-reaching historic renovation 

measures and renewable energy features. During 

publication, the building had achieved ZEB-D status, 

but was continuing to work towards achieving ZEB-A 

status. GSA is using the project to exemplify the “art of the possible” in existing buildings to achieve netzero energy goals. While this is the first of its kind, the hope is that other Federal and private sector 

facility managers will use the lessons learned from Aspinall and not shrink from the challenge to design 

and complete similar projects to determine the parameters for successful historic renovations that include 

net-zero energy measures.

The key lessons learned in the Aspinall renovation project include: 

• Set targets early in the design process and revisit the targets throughout the renovation project to 

determine whether they are being met. Modifying measures and prioritizing targets will help keep 

the team on track to meet the goals established at the outset. 

• Consider tenants and their energy needs early in the process. Some tenants, by virtue of their 

missions, may not agree to commit to zero energy building goals, which could make ZEB-A 

goals unattainable due to limited space for onsite renewables, or increasing costs for ZEB-B, C, 

and D. 

• Assemble a team of dedicated members with the qualifications that will assist in attaining the 

established targets. A passionate, competent team is critical to a successful net-zero energy and 

historic preservation project. Regular meetings with open communication are essential to 

achieving goals. 

• Conduct energy modeling frequently. Frequently updated models that simulate the measures 

needed to achieve net-zero energy goals, and regular team review of the models is essential to 

make informed construction and goal-making decisions. 

• Include energy monitoring and sub-metering to the circuit level. This level of monitoring allows 

teams to isolate building system performance for each piece of equipment installed to ensure 

lowest possible energy draw and optimal performance. From a contract standpoint, it allows the 

 

25 www.gsa.gov/portal/content/180259 

The challenges faced in designing and 

implementing the renovation to meet the 

aggressive goals set by GSA pushed all 

involved to think harder, think smarter, 

and test the bounds of what was thought 

to be possible.
28 

owner to complete a more comprehensive commissioning process that includes energy 

performance as a part of system performance. Monitoring also allows the team/owner/property 

manager to isolate plug load consumption within the building and identify opportunities for 

individual energy use reductions, while also holding manufacturers accountable to meet energy 

performance claims in product literature.

• Include performance assurance or enhanced measurement & verification language in contracts for a 

minimum of one year, post construction. This enables the owner to request the design-build team 

prove they have met contractual energy related targets, which are important to define within the 

contract. M&V should include engineers, designers, contractor, sub-contractors, and manufacturer 

representatives. In addition, it may include other contracts such as the construction manager and 

commissioning agent. The purpose of the enhanced M&V is to evaluate the new system’s postconstruction actual performance as compared to expected energy performance at the design phase.

Enhanced M&V provides an opportunity to engage stakeholders to address system operation issues 

in each seasonal condition and make adjustments to align the system's operation and enhance 

system performance. In this way, enhanced M&V supports the energy design intent and extends 

stakeholders an opportunity to examine ways to enhance performance beyond the design intent if 

possible. This requires, at a minimum, bi-weekly meetings to assess energy data from energy 

monitoring at the circuit level then compare it to anticipated performance. Re-work by subcontractors and manufacturers will most likely be required during this period to meet or exceed 

energy design intents. This scope is much more involved than the traditional commissioning 

process, which primarily focuses on operational performance and adherence to the specifications. 

• Include one year post-occupancy contracts with the Engineer of Record to assist property 

management and O&M contractors to ensure proper management of the building systems.

Contracts may be included in the scope of enhanced measurement & verification and can assist in 

ongoing individual plug load management and occupant behavior. Typical contract language 

requiring 40 hours of training may not be sufficient for on-site O&M property management staff 

to fully understand how new systems are intended to work. Nor does typical contract language 

address every site specific issue which may arise post occupancy. Contracts should allow these 

types of issues and concerns to be addressed by the design professional. The scope may assist in 

identifying performance warranty related issues, which may otherwise not be addressed and 

should bridge learning gaps to ensure systems are managed per the design intent. Contract 

language should allow the building manager and O&M contractors or staff to meet with the 

engineer on an established basis through the one-year period to ask questions about systems and 

maximizing performance. The intent of this type of contract is to allow property managers and 

O&M contractors to properly manage new equipment to ensure the longevity and enhanced 

performance of the new systems. Since building automation system (BAS) program logic may 

need to be changed based on outcomes of discussions among property management staff and the 

engineer, it may be beneficial to allocate funds for the BAS programming contractor. 

GSA’s experience shows that historic renovations incorporating net-zero energy goals can be considered 

in three discrete, sequential parts: historic renovation measures that align with deep energy retrofit or high 

performing new construction, post-occupancy modifications, and finally purchase of renewable energy. 

The deep energy retrofit or high performing new construction is the largest investment. Energy 

performance should be monitored and addressed for a period of 1–2 years post-construction with 

occupants present in the building. During the 1–2 years post-construction, the project team should attempt 

to address tenant plug loads, engaging stakeholder tenants to reduce associated energy use to its bare 

minimum. Although monitoring in post construction will reveal much about tenant plug loads, tenant 

behavior modifications and information technology equipment discussions can begin long before the 
29 

project is initiated and continue long after the project ends. Once the post construction M&V is complete, 

plug loads can be better estimated based on the one year post occupancy. 

The final phase should be the installation of renewable energy resources to compensate for the post 

occupancy energy demand. It is important to design buildings to be “renewable energy ready” so that 

solar PV or other technologies can be installed when they are financially viable. Early installation of 

renewable energy resources based on expected energy use runs the risk of miscalculating the necessary 

investment in renewable energy. Monitoring the building for one to two years post occupancy will 

provide an accurate energy profile and allow more informed decisions to be made regarding the amount 

of renewable energy needed to meet the building’s energy goals.

The Aspinall Courthouse net-zero energy renovation has been a learning experience for the GSA, and the 

lessons-learned are valuable to the Federal government as each agency strives to meet net-zero energy 

goals. The successful completion of the Aspinall Courthouse historic preservation and net-zero renovation 

has set the bar high, and illuminates continuing steps on the path toward meeting national energy and 

sustainability challenges, with the Federal government leading the way. 

The Aspinall renovation is one of the first historic renovation projects that incorporates net-zero energy 

aspects. As a result, the total costs of the project are challenging to benchmark with other similar projects. 

The Aspinall renovation was approximately $264/ ft2

, which included the costs of the solar PV 

installation. The National Renewable Energy Laboratory constructed the Research Support Facility 

(which is a net-zero new construction) for approximately $240/ ft2 without the solar PV installation. The 

national average cost for office buildings that incorporate energy efficiency measures, such as LEEDcertified building projects, is $333/ ft2

. GSA believes the design-build contract and whole-building design 

approach kept the costs lower than they would be without these approaches. Costs were also lower due to 

the original design of the Aspinall building, which already incorporated features such as natural daylight

and thermal comfort with passive design. Preservation and net-zero costs may have been much higher 

without these original design features. As more historic renovation projects incorporate net-zero energy 

aspects, the total costs of the projects would be interesting to compare. 
DOE/GO-102014-4462, October 2014

For more information, visit:

femp.energy.gov